Currently the major process by which hydrogen is produced is by the steam reforming of methane. Another means of making hydrogen is by the electrolysis of water. The electricity required for electrolysis is mainly derived from the electric power grid, and the predominant source of grid electricity, combustion of fossil fuels, generates emissions, such as nitrogen oxides and particulate matter, as well as carbon dioxide. One way to eliminate such emissions is to use solar generated electricity to electrolyze water to make hydrogen. Presently, efforts are directed toward improving the efficiency, durability, and cost of the hydrogen production processes. Small PEC devices using specially coated research-grade amorphous silicon (a-Si) solar cells, together with a platinum electrode housed in a small quartz cell are disclosed in U.S. Ser. No. 10/662,853; filed Sep. 15, 2003 and U.S. Ser. No. 10/608,509; filed Jun. 27, 2003, incorporated herein by reference in their entirety as a general teaching tool.
However, systems consisting of solar cells to make electricity together with electrolyzers to dissociate water into hydrogen and oxygen are costly compared to producing hydrogen by the steam reforming of methane. These attempts have been made to produce hydrogen gas to supply vehicle-fueling stations by using electricity from photovoltaic panels and commercially available electrolyzers to split water. These projects have proved unsatisfactory and were usually short-lived due to the low efficiency and high cost of the combined technology, which only converted 2% to 6% of the solar energy to hydrogen fuel energy, thus greatly increasing the costs, the resulting hydrogen fuel cost (at least $11 per kilogram of hydrogen), and the large area covered by the system.